Realme
Set Custom Notification Sound auf Realme
Realme UI ships with a limited set of preinstalled notification tones. If none of them fit, you can add your own audio file and select it as a custom notification sound instead of relying on the defaults.
The system only lists files that are actually saved on the internal storage of your realme device and use a supported audio format such as mp3. If the file was never copied over, or ended up in a location the sound picker does not scan, it simply will not show up when you try to select it.
To set your own file as the notification sound, open Settings ➔ Sound & vibration ➔ Notification sound ➔ Select from files. From there you can browse the internal storage and choose the mp3 you copied earlier.
This method works for the general notification sound used by most apps. Some apps manage their own sound settings separately, so a custom tone set here may not apply everywhere.
If you only want a different sound for one specific app, check that app's own notification settings first before changing the system-wide tone.